Brenda Eskenazi is a neuropsychologist and epidemiologist, and a professor at the School of Public Health at the University of California, Berkeley. She has spent more than 30 years examining the effects of environmental exposures on male and female fertility, pregnancy, and children’s health and development. Her studies show that the exposure not only during childhood but as early as in utero might have effects that last for life and could even affect the next generations.
She was recently in Barcelona to attend the annual conference of the International Society for Environmental Epidemiology, and we took the chance to interview her about the challenges of her research, and what we can do to protect our health, and our children’s health.
You studies show that children exposures might have later effects in life. What kind of consequences are we talking about?
In general we are concerned about early life exposure –including in utero exposure- and effects in childhood, because those effects might have associations with later effects in life. For example, there is some evidence that a child that has decreased lung function as an adolescent will still have it as an adult. Or a child that has low IQ will continue to have it all his or her life. But there might be also some direct effects from children or fetal exposure on adult life. For example, when women took DES or Diethylstilbestrol in the 1950s to prevent miscarriage, that resulted in a small proportion of women getting vaginal cancer, and some become infertile, but also on some of their children having lower fertility. It’s a second generation effect. We are now trying to see if there is something similar happening with chemicals and the environment. Can we affect the health of the future generations with the exposures they are having in utero?
Which effects of early or in utero exposures do we know already? In which circumstances have they occurred?
We know that some exposures to chemicals or radiation might cause permanent changes that cannot be reversed and might affect that child’s health –physical or psychological- for life. The most evident data we have are from extraordinary cases such as the nuclear bombs in Hiroshima or Nagasaki, where besides the direct deaths, there were consequences in fetus: less weight and height, higher blood pressure and more tumors. Children born after the Chernobyl accident in the radiated areas presented lower IQ and higher rates of thyroid cancer. Girls had a higher level of testosterone too. The dumping of tons of mercury in Minamata, Japan, in 1956, has caused congenital cerebral palsy, impairment of intelligence, and dementia, among others. The chemical accident in Seveso, Italy, in 1976, has had effects on the menstrual cycle, infertility and a higher risk of cancer. Those are extreme cases, but they prove that the exposure to chemicals in utero or at an early age has an effect on human health, for life.
Besides these extreme conditions of chemical accidents, what is the effect of the lower doses we are exposed to in our everyday life?
There are effects from low doses too, and from products we have around on a daily basis.
One clear example is maternal smoking. We know that it causes lower weight at birth, but that is not all. Because of that low weight, that child might have bad health over the years, and we have also seen a relationship linking maternal smoking and adult obesity, hypertension, diabetes and low fertility on those sons and daughters.
Another example is lead. It is well-known that there is an association between high lead levels and criminality. And insecticides like DDT, for girls who had been exposed before being 14, has been associated with breast cancer. There are other studies that are looking at the effects of the fire retarders that we used in the past, and there are also evidences on air pollution and their continuous effects on health. There are many organs that can be affected by environmental exposure, and one of the things that are very important and really understudied is how these environmental agents affect the immune system. That is, our ability to respond to different infections, or our ability to respond to vaccinations appropriately.
The fact is that there are not many studies out there in terms of human health and early exposures, so far. (There are some more based on animals though). And it is still unclear if this relationship is causal, we need to do more research with human data. And it is necessary to do it. We need more information.
Could the every day more frequent alterations in puberty also be a consequence of some early exposure?
It is not an easy topic as there are a number of things that are happening at the same time. We are seeing more chemicals in the environment, endocrine disruptors that affect the hormonal system… But we are also seeing, in animals, that some of the chemicals might affect obesity, weight. If it is true also in humans, we know that weight has a very interesting relationship with the onset of puberty. We don’t know what comes first, the chicken or the egg. But body mass changes before puberty and around puberty are important. It is still unclear whether it is one chemical that triggers both of them at the same time, or if it is a chemical that triggers changes in weight that then triggers puberty, or viceversa. Fat food could also be the cause, as it creates obesity, that might be causing early puberty. So it’s not a simple answer.
But at this meeting we have had several presentations talking not only about early puberty but also about late puberty, and either one of them can have adverse consequences. Both of them put the breasts at some risk. Especially with the early puberty, there are well-known associations as being a risk factor for breast cancer.
We recently reported on a paper the relationship between organophosphate pesticides, which are widely used in agriculture, and metabolized in the mother during pregnancy, and the IQ of the child of seven years of age. We previously reported that these pesticides can also be related to deficit disorder and hyperactivity. At the same time, two other studies have similar results. And the convergence of these findings lead us to think: do we see neurotoxic associations related to low levels of exposure to organophosphate pesticides? We know that the association exists on high levels but the question is if they also occur on low levels, on the levels we are all exposed to. We really don’t know the answer yet, because the measures of these chemicals in the human body are complicated, but data seem to suggest that there are effects.
With all these information, parents might feel some degree of alarm and wonder what they can do to protect their children.
There are things that one can do, practical details that might not be a complete solution, but that can make a difference. Number one: do not microwave in plastic. Actually, use as little plastic as possible. If you want to microwave, do it in glass. If possible, drink out from glass or stainless steel or aluminum containers. In terms of pesticides, I don’t promote eating organic because it is often out of the price range for many people, and the most important thing for me about pregnant women is that they take their fresh fruit and vegetables, that is organic or not. And it is also important to wash your fruits and vegetables very well, and that means that, if you can, you use a scrub brush to wash the residues off the fruits and vegetables. Some people ask if they need to use some kind of soap or some special cleanser, and I say no, just use running water to clean it well. And that means even cleaning a watermelon or a melon before you cut into it. That is to prevent from the rests of pesticides.
Also do not use any kind of coated cooking equipment –pans, for example- if you suspect that it might have some chemicals in it. So there is a variety of practical things that one can do to safeguard your baby, and I specially promote that pregnant women do this. And of course, stay away from anybody smoking cigarettes and absolutely don’t smoke yourself. Or dink alcohol, we don’t know a safe level of alcohol consumption during pregnancy.
Research on children’s environmental health has increased a lot in the last few years. What are the challenges you face in this field?
I have being doing this stuff for 30 years, and when I started in this, I could count on one hand the number of people who were working on children’s environmental health. In the last decade, I have seen a mushrooming of studies on effects of chemicals on children’s health, and on fetal health. At this meeting we are seeing a huge number of studies on this topics, more than ever. So I think that we are going to see a lot of information coming out in the next few years. Because of this, we have created the International Society of Children’s Health and the Environment (ISCHE), to bring together the people who are working on it, so we can begin to produce white papers or other documents that summarize our work so that policy makers can see what the scientist think that the results are. I think we have come to a good place in our field. It makes me feel very good that we will have more information for the future generations, I think it is hopeful.
But for all this research to progress, we need the cooperation of many people. Most of these studies are based on the data of the people who accept to share their information for scientific purposes. And I can only speak for myself: I have been a participant in many studies. I feel that way I can contribute to give something back to society and make sure there is enough information about human health. And as a parent, too. My son has been in studies as well. Of course I would never do anything that would harm him, but these studies are based on informative data. It is not something to be afraid of at all. We will never get good information for us or for our children, or for our children’s children, unless we participate in those studies. That is essential for the future generations. If you want to have healthy grandchildren, be part of that movement.
We need more data to confirm our hypothesis, and to extend our research too: so far we have focused on the mother’s exposures, but what about the father? How does the sperm exposure affect the children’s health?
We need to know more.
Brenda Eskenazi is the Director of the Center for Environmental Research & Children’s Health.
Roger Torné Foundation, recognizing the need for research in this field, is working with the Center for Research in Environmental Epidemiology (CREAL) in a major project to study the role of pollutants in the air, water and diet on children’s health, involving hundreds of altruistic families. On the other hand,you will find more information and measures to protect children’s health in the ‘Children’s health and environment: a relationship for life’ guide, published by the Foundation and based on the results of more than 150 scientific studies worldwide.